\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=stealth,domain=.45:4.5, samples=100]
  \draw[<->] (0,5)node [right]{$p$（\unit{atm}）}--(0,0)--(5,0) node [right]{$V$（\unit{L}）};
  \foreach \x in {1,2,3,4}
    {
      \draw (0,\x)node [left]{\x}--(.1,\x);
      \draw (\x,0)node [below]{\x}--(\x,.1);
    }
  \draw[color=black, ultra thick] plot (\x,{2/\x}) ;
  \draw [dashed] (1,0)--(1,2)--(0,2);
  \draw [dashed] (2,0)--(2,1)--(0,1);
  \draw [dashed] (4,0)--(4,.5)--(0,.5);
  \draw [dashed] (0.5,0)--(.5,4)--(0,4);
  \draw [fill=black] (1,2)node [right]{$C$}  circle (2pt);
  \draw [fill=black] (2,1)node [above]{$A$}  circle (2pt);
  \draw [fill=black] (4,.5)node [above]{$B$} circle (2pt);
  \draw [fill=black] (.5,4)node [right]{$D$} circle (2pt);
  \node at (-.2,-.2){$0$};
\end{tikzpicture}
\end{document}